Combine the eggs and granulated sugar in the top of a stainless steel double boiler and, being careful not to scramble the eggs, whisk over gentle heat until the mixture is golden in color and thick enough to coat the back of a spoon in ribbons. Remove from the heat and set the mixture aside to cool.
While the egg mixture is cooling, prepare four 1/2 cup souffle dishes by cutting waxed paper long enough to encircle each souffle dish twice, and stand 3 to 4 inches above its top. Wrap the waxed paper snugly around the outside of the dish and seal the edges with transparent tape. Butter the inside of the dish with softened butter, then sprinkle with granulated sugar, tapping out any excess sugar onto a plate.
Using an electric mixer, combine 1 cup of the heavy cream, confectioners sugar, and Grand Marnier, orange zest and whip into firm peaks. With a spatula, gently fold the whipped cream into the egg mixture. Pour the mixture into the buttered souffle dishes, filling them above the rim and into the area enclosed by the waxed paper.
Place the souffles into the freezer, for at least 4 hours, preferably overnight. When ready to serve, whip the remaining cream until soft peaks form, remove from the frozen souffle from the freezer, and carefully remove the waxed paper collar. Top with a dollop of whipped cream and several orange segments.